Method of preparing polyaryl selenazoles



Patented Jan. 11, 1944 r UNITED STATES PATENT OFFiCE METHOD OF PREPARING POLYARYL SELENAZOLES Edmund B. Middleton, Woodbridg'e, and George A. Dawson, Stelton, N. J., assignors, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 25, 1939, Serial No. 301,296

8 Claims. (Cl. 260-298) This invention relates to new and useful polyhave developed a new and more practical method aryl selenazole compounds and to a new and imthan that of British Patent No. 389,969. This proved method for producing such compounds. method is described in their co-pending United The invention is particularly concerned with the States patent application'Serial'No. 78,734. With production of selenazole derivatives containing a respect to 2 methyl beta-naphthselenazole,

compounds exceedingly diflicult to prepare. elsewhere, they have developed the process which The term polyaryl selenazole is used to deis a subject of this applicationscribe polyheteroatomic ring compounds contain- It may be observed that the clifilculty of reacing two or more condensed benzene rings and 10 tion resulting in the production of azoles concontaining nitrogen and selenium in the heterotaining members of the oxygen group of elements cyclic ring structure as the hetero atoms. in the azole ring may vary greatly with diiierent Many of the simple azoles consisting of a single elements, becoming greater in proceeding from ring nucleus have been known for years. Hantzsch the non-metallic elements such as oxygen and (Ber. 21, 945) described a 2-methyl oxazole in sulfur to the more strongly metallic elements 1888. The 2-methyl thiazole bases have also such as s -enium and tellurium. This probably been known since 1888 (Annalen, vol. 250, pp. accounts for the fact that many of the oxazoles 257-280). A 2-methyl selenazole base was deand thiazoles have been known for years while scribed by Hoffman, Annalen der Chemie 250, the p epa o o most of the Selenazoles has been accomplished more recently and some of The base Z-methyl benzoxazole was described them are still unknown even though the correin 1876 by Ladenburg, Ber. 9, 1924. The-Z-methspending oxazoles and thiazoles are known. yl benzothiazole base has been known since 1880, Furthermore, the tellurazoles from the simplest Hoffman, Ber. 13, 1236. The Z-methy] benzoselto the more complex derivatives have not been enazole base has been known since 1928, Clark, described up to the present time.

J. C. S. (1928) pp. 2313-20. As a general rule, moreover, the more complex Of the naphthoxazoles, the 2-methyl alpha the compound and the heavier its molecule, the

naphthoxazole base has been known since 1883, more difiicult it is to prepare. Thus, a naphtho- B911 1933- e et y1 pha naphthothiselenazole is more difiicult to prepare than a azole base has been known since 1898, Ber. 20, benzoselenazole. Additionally, a general type of 1800. According to British Patents Nos. 386,791 reaction which can be used in making one comand 389,969, pseudocyanine and isocyanine dyes pound often cannot be used in making a closely can be made from the methyl salts of 2-methyl related compound. For example, we have pre alpha naphthoselenazole, although the properpared the base alpha naphthoselenazole by sevties of the base are not described. The latter era] series of reactions, but the same series of repatent indicates that this base can be made from actions could not be used conveniently to pro l-amino-Z-nitro naphthalene by diazotization duce the isomeric beta naphthoselenazole base.

followed by treatment with potassium selenocy- One of the objects of this invention is the proanide to replace the diazo group by the group vision ofanew and improved, commercially prac- SeCN, then reducing the resultant product by tical series of reactions for producing new and means of sodium hydrosulfite in the presence of useful compounds containing a beta naphthoselcaustic potash to produce 2-aminol-seleno enazole nucleus.

naphthol, oxidizing this compound to 2:2'-di- A more specific object has been the preparaamino-1:1'dinaphthyl diselenide, and treating tion for the first time of the base beta naphthothe latter with zince and acetic anhydride to proselenazole and quaternary salts thereof. Other duce Z-methyl-alpha-naphthoselenazole. objects will appear hereinafter.

While it is theoretically possible to produce the These objects are accomplished in accordance compounds mentioned, the series of reactions dewith this invention by reacting a selenohydrate,

scribed, when applied to polyaryl derivatives preferably sodium or potassium selenohydrate, such as amino nitro naphthalenes, present so upon an alpha intro-beta-halogeno-naphthalene much difiiculty as to be impractical commercially, compound in a non-oxidizing atmosphere, prefand the present applicants have, therefore, erably in an atmosphere of hydrogen, and treatsought to develop a new process for the manuing theresultant reaction product with a reducfacture of 2-methyl naphthselenazoles. In the his agent capable of reducing a nitro group to case of 2-methyl alpha naphthselenazole, they an amino group, preferably a metallic reducing agent, such as zinc, and an aliphatic carboxylic acid, for example, acetic anhydride, thereby forming a beta naphthoselenazole. The reduction of the nitro group to the amino group and closing of the selenazole ring occur simultaneously or contemporaneously.

The general equations illustrating the course of reactions starting with beta-amino-naphthalene may be illustrated as follows:

NHs

acid anhydride of an NHZ acylation followed by nitration and the hydrolysis of the nitro-acyl compound SeH Zn (RCOMO where R lower alkyl groups.

The above equations are intended to represent generally the course of the reactions, but it will be understood that the process of the invention contemplates the particular steps involved, regardless of whether the foregoing equations represent all of the reactions taking place.

In this way, it has been possible for the first time to prepare the base Z-methyl beta naphthoselenazole and other compounds containing a beta naphthoselenazole nucleus, from l-nitro- Z-chloro-naphthalene. This compound has the general formula:

C- CH3 It is obtained as cream colored crystals melting around 102-l04 C.

The following examples in which the quantiin parts by weight will serve to but are not in- EXAMPLE I Preparation of 2-methyl beta naphthoselenazole Twenty-five (25) parts of 1-nitro-2-chlornaphthalene was dissolved in about 160 parts of ethyl alcohol in a three neck vessel equipped with a stirrer reflux condenser and gas inlet tube that ran to the bottom of the vessel. A solution of potassium selenohydrate (KSeH) was prepared by dissolving 6.8 parts of potassium hydroxide in about 80 parts of ethyl alcohol and saturating it at 15 C. with 151286. The HzSe (hydrogen selenide) was generated by dropping very dilute hydrochloric acid upon aluminum selenide (AlzSeg) The vessel containing the nitro-chlor-naphthalene solution was filled with hydrogen to the complete exclusion of air, and then while stirring, the KSeI-I solution was added rather quickly down the condenser. Heat was generated and the vessel was cooled to control the reaction. With the subsidence of the reaction, the vessel was warmed with steam for one hour. The stirrer and reflux condenser were then removed and the contents evaporated to dryness with the aid of steam and vacuum.

Acetic anhydride (216 parts) was then added. The hydrogen line was removed and the reflux condenser replaced. The solution was heated to reflux and reduced with 35 parts of zinc dust. Refluxing was continued for one hour after the zinc had been added. The reaction took place violently and the zinc was added at intervals in very small portions. Aiter reduction was complete, the solution was cooled and filtered, and the filtrate vacuum distilled. The distillate below was discarded and the fraction distilling from -220 C. was redistilled, the distillate finally collected being from The distillate was a yellow oil that soon crystallized. When recrystallized from alcohol, the base 2-methyl beta naphthoselenazole was obtained as cream colored crystals melting from i02-10 C.

Nitro-chlor-naphthalene for this reaction may be prepared by the Sandmeyer reaction upon diazotized nitronaphthylamine according to the method of Hodgson and Walker, J. C. S. (1933) p. 1620.

Aluminum selenide may be prepared by mixing together intimately calculated quantities of powdered aluminum and selenium and. igniting the reaction by magnesium ribbon or a mixture of sulfur and potassium chlorate. The reaction is best conducted at a safe distance. It is dangerously violent and care should be taken not to breathe too deeply of the fumes.

The 2-methyl beta naphthoselenazole base forms quaternary salts by reaction with esters of organic and inorganic acids, e. g., dimethyl sulfate, diethyl sulfate, ethyl paratoluene sulfonate, ethyl iodide, methyl iodide, propyl iodide, ethyl bromide, methyl bromide, propyl bromide, allyl iodide, allyl bromide and the corresponding chlorides and perchlorates as well as higher alkyl homologues. These compounds have the following general formula:

R\ x N 3\ 2C-CH2 Se in which R is alkyl (e. g., methyl, ethyl, propyl) and X is a salt forming radical (e. g., chlorine, bromine, iodine, methsuliate, ethsulfate, perchlorate, etc).

These new compounds may be used to make new and useful dyes which may be employed for various purposes, e. g., for dyeing materials and in photography for addition to photographic emulsions as sensitizers and for other purposes.

The following examples are given as typical of the use of these new compounds in preparing new and useful dyes:

EXAMPLE II Preparation of 3:3'-dimethyl beta naphthoselenocarbocyamne bromide One part of the base Z-methyl beta naphthoselenazole and about .5 part of dimethyl sulfate were heated in a sealed tube for three days at 95 C. The melt was then dissolved in parts of pyridine and 2.7 parts of ethyl orthoformate. Upon heating this solution to reflux a green-blue color developed. After one hour refluxing the solution was treated with excess aqueous potassium bromide solution and cooled. The dye was obtained as fine purple crystals which were recrystallized twice from alcohol.

When tested in silver halide photographic emulsions, this dye showed pronounced sensitizing properties, being a relatively weak sensitizer for silver bromide emulsions containing a small amount of silver iodide but a very powerful sensitizer in silver chloride emulsions, sensitizing in the red region of the spectrum with a blind spot in the green region.

EXAMPLE III Preparation of 3-methyl-1-ethyl beta naphthoselenazole pseudocyanine iodide One part of 2-methyl beta naphthoselenazole prepared as in Example I was heated with .54 part of dimethyl sulfate for three days in a sealed tube at 95 C. The melt was then dissolved in 20 parts of absolute alcohol and 1.2 parts of methylthiocarbostyryl ethiodide were added to the solution which was heated to reflux and treated with 0.5 part trimethylamine. developed and after one hour, refluxing was discontinued and the solution cooled. Red crystals of the dye separated, were filtered and recrystallized twice from alcohol. Their alcoholic solution was similar in color to that of erythrosine. This dye also exhibited marked sensitizing power in silver halide photographic emulsions.

The invention is subject to variations and modifications in the manner of its practical application. The beta naphthoselenazole base and salts thereof may contain a substituent other than methyl in the 2-position, e. g., a higher alkyl group such as ethyl. This may be accomplished by using chemically equivalent proportions of propionic anhydride or a higher homologue instead of acetic anhydride in the previously described reactions.

The procedure for making the nitro amino naphthalene described generally in the first series of Equations 1 may be carried out in a known A red color manner by first acylating the amino to block any reaction of the nitrating acid with the amino group, and then nitrating the acylamino naphthalene to produce a nitro-acylamino naphthalene. Hydrolysis of this product in a known way splits oif the acyl group leaving the nitro amino naphthalene.

In the second series of reactions 2, the halogen atom of the nitro-halogeno naphthalene may be chlorine, bromine or iodine. A solvent or reaction medium which is substantially inert, for example, alcohol, is preferably used in carrying out the third series of reactions 3. Other inert solvents may be used; Other metallic selenohydrates may also be used, although the alkali metal selenohydrates are preferred. Temperatures at which refluxing will occur in the fourth series (4) will be determined largely by the specific acid anhydride employed. Thus, the temperature of refluxing will be higher with propionic anhydride than with acetic anhydride. The temperature employed in any case should be insufficiently high to cause the desired products to be destroyed by decomposition. If it is desired to reduce the refluxing temperature, a lower pressure may be employed.

The steps of the process, and the series of reactions herein described, are applicable to the preparation of any beta naphthoselenazole base and the quaternary salts thereof.

The invention makes possible the preparation of an entirely new series of compounds having a wide variety of uses, for instance, as dye intermediates, dyes, sensitizers for photographic emulsions and for other purposes.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In a method of making a beta naphthoselenazole, the steps which comprise treating an alpha nitro-beta-halogeno naphthalene with a selenohydrate in a non-oxidizing atmosphere, and treating the resultant reaction product with a reducing agent capable of reducing a nitro group to an amino group and with an anhydride of an aliphatic carboxylic acid.

2. In a method of making a beta naphthoselenazole, the step which comprises treating a 1- nitro Z-halogeno naphthalene with an alkali metal selenohydrate in an atmosphere of hydrogen and treating the resultant product with zinc and acetic anhydride.

3. In a method of making the base Z-methyl beta naphthoselenazole, the steps which comprise treating l-nitro 2-crloro naphthalene with potassium selenohydrate in alcohol solution in an atmosphere of hydrogen while cooling the reaction mixture, then evaporating the resultant reaction product to dryness, mixing acetic anhydride therewith and adding zinc in finely divided form while refluxing, then cooling, filtering and vacuum distilling the filtrate, thereafter redistilling the fraction of the filtrate boiling from to about and separating the 2-methyl beta naphthoselenazole base from said fraction by crystallization. 4. In a method for the preparation of a beta naphthoselenazole, the steps which comprise treating an alpha-nitro-beta chlornaphthalene with an alkali metal selenohydrate in a non-oxidizing atmosphere and treating the resultant reaction product with a reducing agent capable of reducing a nitro group to an amino group.

5. In a method for the preparation of a beta naphthoselenazole, the steps which comprise treating an alpha nitro-heta-halogeno naphthalene with an alkali metal selenohydrate in a nonoxidizing atmosphere, and treating the resultant reaction product with a reducing agent capable of reducing a nitro group to an amino group.

6. In a method of making a Z-methyl beta naphthoselenazole, the steps which comprise treating l-nitro 2-ch1oro naphthalene with a selenohydrate in a non-oxidizing atmosphere, and treating the resultant reaction product with a reducing agent capable of reducing a nitro group to an amino group and with acetic anhydride.

'7. In a method of making a 2-methy1 loeta naphthoselenazole, the step which comprises treating l-nitro Z-chloro naphthalene with an alkali metal selenohydrate in an atmosphere of hydrogen, and treating the resultant product with zinc and acetic anhydride.

8. In a method of making a 2-methyl beta naphthoselenazole, the step which comprises treating a l-nitro Z-halogeno naphthalene with potassium selenohydrate in an atmosphere of hydrogen in the presence of a substantially inert solvent medium, and treating the resultant prodnot with zinc and acetic anhydride.

EDMUND B, MIDDLETON. GEORGE A. DAWSON.

CERTIFICATE OF CORRECTION. Patent No. 2,559,09h. January 11, 19th.

EDMUND B. MIDDLETON, ET AL of the above numbered patent requiring correction as follows: Page 1, first column, line 22, for "192A" read "1 2A"; andthat the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

